Why one call bridge twice

== Using SIP RTP CoS mark 5
== Using UDPTL CoS mark 5
– Called 2139
[Mar 28 19:27:39] WARNING[1689]: res_musiconhold.c:1001 moh_scan_files: Cannot open dir /var/www/html/moh/railway or dir does not exist
– Started music on hold, class ‘railway’, on channel ‘SIP/2138-00000062’
– SIP/2139-00000063 is ringing
== Manager ‘admin’ logged on from 220.249.187.114
– SIP/2139-00000063 answered SIP/2138-00000062
– Stopped music on hold on SIP/2138-00000062
– Native bridging SIP/2138-00000062 and SIP/2139-00000063
– Native bridging SIP/2138-00000062 and SIP/2139-00000063
what reaseon?
meida?